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排序方式: 共有412条查询结果,搜索用时 15 毫秒
1.
Dr. Yalcin Cetin 《Cell and tissue research》1988,253(1):173-179
Summary It has long been disputed whether mammalian enterochromaffin (EC-) cells contain a peptide in addition to serotonin. Previous immunohistochemical studies have provided evidence for the presence of enkephalins in EC-cells. These findings, however, are equivocal. Therefore, the problem of opioid peptides in EC-cells has been re-examined in the gastro-intestinal mucosa of dog, guinea-pig and man. A battery of antisera against derivatives of pro-opiomelanocortin, pro-enkephalin and pro-dynorphin have been applied to semithin serial sections of the tissues, in combination with fluorescence histochemistry and serotonin immunocytochemistry. Our findings indicate that EC-cells of the investigated species contain pro-dynorphin-related peptides, i.e. dynorphin A and -neo-endorphin, but no derivatives from pro-opiomelanocortin or pro-enkephalin. Since remarkable interspecies variations occur with respect to the number and staining characteristics of opioid immunoreactive EC-cells, it is concluded that pro-dynorphin shows specific routes of post-translational processing depending upon the species and the gastro-intestinal segment investigated. Future studies should focus on the mutual relationships between serotonin and dynorphins and on the physiological significance of these peptides in the gastrointestinal tract.Part of the results were presented at the Bayliss and Starling Society National Scientific Meeting 1985, London (Cetin et al. 1985) 相似文献
2.
Nicoletta zini Patrizia Sabatelli Irene Faenza Andrea Ognibene Nadir M. Maraldi 《The Histochemical journal》1996,28(7):495-504
Summary Some key elements of signal transduction have been identified within the nucleus and demonstrated to be responsive to specific
agonists in numerous cell types. In particular, mitogenic stimuli have been reported to induce, a transient increase of the
nuclear phospholipase C β1 activity, causing the release of inositide-derived second messengers, whereas differentiating stimuli induced a decrease
of the enzyme activity and an increase of nuclear phosphatidylinositol 4,5-bisphosphate (PIP2). Recently, we reported evidence, in human osteosarcoma Saos-2 cell lines, on the presence of specific nuclear phospholipase
C isoforms and on the activation of phospholipase C β1 in the nucleus following the exposure to interleukin-1α. In this study we report immunocytochemical ultrastructural evidence on quantitative variations of PIP2 and phospholipase C β1 amounts in the nucleus of Saos-2 cells at different times of exposure to interleukin-1α. After short periods of culture in the presence of the agonist, the intranuclear amount of PIP2 is decreased, while a translocation of phospholipase C β1 occurs from the cytoplasm to the nucleus, in correspondence with the increased hydrolyzing activity of the enzyme. After
longer periods of incubation with interleukin-1α, on the other hand, the intranuclear amount of PIP2 is restored to initial level, while the amount of phospholipase C β1 is increased both at the nuclear and cytoplasmic level, when its activation is no longer effective. The results, compared
with those obtained in other cell types responsive to given agonists, account for a cell-specific modulation of signal transduction
based on polyphosphoinositide breakdown at the nuclear level. 相似文献
3.
Spartaco Santi Silvia Rubbini Caterina Cinti Stefano Squarzoni Alessandro Matteucci Elisabetta Caramelli Lia Guidotti Nadir M. Maraldi 《Biology of the cell / under the auspices of the European Cell Biology Organization》1994,81(1):47-57
Summary— In the sperm nuclei the DNA is packaged into a highly condensed form and is not organized into nucleosome and solenoid but is bound and stabilized mainly by the protamines that arrange the DNA in an almost crystalline state. As demonstrated for somatic cells, the sperm DNA has been reported to be organized in loop domains attached to the nuclear matrix structures. However, the possible role of the sperm head matrix in maintaining the loop organization in absence of a typical nucleosomal structures has not been fully elucidated. By using in situ nick translation at confocal and electron microscope level, we analyzed the organization of the DNAprotamine complex and its association with the sperm nuclear matrix. The data obtained indicate that the chromatin organization in sperm nuclei is maintained during the sperm condensation by means of interactions with the nuclear matrix at fixed sites. The fine stucture of sperm nucleus and of sperm nuclear matrix, investigated on sections and replicas of freeze-fractured specimens, suggests that the lamellar array, observed by freeze-fracturing in the sperm nuclei, could depend on the inner matrix which presents a regular organization of globular structures possibly involved in the maintenance of chromatin domains in highly condensed sperm nuclei also. 相似文献
4.
Safak Yalcin Hirohiko Kuratsune Koji Yamaguchi Teruo Kitani Koichi Yamanishi 《Microbiology and immunology》1994,38(7):587-590
Peripheral blood mononuclear cells collected from 13 patients with chronic fatigue syndrome and 13 healthy controls were analyzed for the presence of human herpesvirus 6 (HHV-6) DNA by variant-specific polymerase chain reaction and dot blot hybridization. HHV-6 DNA was detected in 7 of 13 (53%) patients, and of those 7 patients, 4 were positive for HHV-6 variant A DNA and 3 were for variant B. No HHV-6 DNA was detected in the controls. Serum antibody titers to the late antigen and antibody prevalence to the early antigen of HHV-6 were significantly higher in the patient group. These results suggest active replication of HHV-6 in patients with chronic fatigue syndrome. 相似文献
5.
Identification and characterization of E.coli ribosomal binding sites by free energy computation. 总被引:4,自引:0,他引:4
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Sequences upstream from translational initiation sites of different E.coli genes show various degrees of complementarity to the Shine-Dalgarno (SD) sequence at the 3' end of the 16S rRNA. We propose a quantitative measure for the SD region on the mRNA, that reflects its degree of complementarity to the rRNA. This measure is based on the stability of the rRNA-mRNA duplex as established by free energy computations. The free energy calculations are based on the same principles that are used for folding a single RNA molecule, and are executed by similar algorithms. Bulges and internal loops in the rRNA and mRNA are allowed. The mRNA string with maximum free energy gain upon binding to the rRNA is selected as the most favorable SD sequence of a gene. The free energy value that represents the SD region provides a quantitative measure that can be used for comparing SD sequences of different genes. The distribution of this measure in more than 1000 E.coli genes is presented and discussed. 相似文献
6.
Charles Pouchon Jérémy Gauthier Camille Pitteloud Cyrille Claudel Nadir Alvarez 《植物分类学报:英文版》2023,61(1):64-79
Encompassing ca. 200 species distributed in paleotropical Africa and Asia, Amorphophallus is one of the largest genera of Araceae. In spite of the great economic interest in its glucomannan production, only a few studies have attempted to grasp the evolutionary history of this genus. In the current state of knowledge, four main clades, mostly linked to biogeographical delineation, have been identified from phylogenies based on a few genes. However, relationships among and within these clades still remain unclear, due to the rapid radiation that occurred during the early evolutionary history of the genus. Here, we generated genome skimming libraries for 43 specimens from 36 species distributed across the 4 clades, which allowed us to produce a phylogenetic matrix for a set of 71 plastid genes. Our phylogenies confirm the monophyly of these clades but show a new and well-resolved arrangement among these clades. Our analyses therefore provide a new scenario and timeline for the evolution of the main Amorphophallus clades, consistent with the morphological characteristics of the clades. The inferred scenario is also in agreement with climate dynamics and the onset of long-distance dispersal by the earliest migratory birds near the Oligocene/Miocene transition around 23 million years ago. Our study provides an up-to-date baseline to understand biogeographic and ecological processes that shaped the current diversity and distribution of Amorphophallus, paving the way for larger-scale phylogenomic studies based on plastid and nuclear genomes. 相似文献
7.
Nicoletta Zini Katia Scotlandi Nicola Baldini Giuseppe Nini Patrixia Sabatelli Nadir M Maraldi 《Biology of the cell / under the auspices of the European Cell Biology Organization》1995,84(3):195-204
Summary— Multidrug-resistant (MDR) variants of a human osteosarcoma cell line (U-2 OS) have been recently obtained by continuous exposure to doxorubicin (DX). The growth and phenotypic characteristics of these cell lines have been demonstrated to be related to the level of expression of P-glycoprotein. In this work, the morphological changes associated with MDR have been evaluated by quantitative image analysis and transmission electron microscopy. Resistant cells present morphological changes with respect to sensitive cells at both cytoplasmic and nuclear level. Some of these changes appear to be related to the degree of resistance but not to the direct presence of DX, since deprived cells maintain some modified characters, while others are partly lost. These findings suggest that DX exposure affects cell metabolism causing progressive changes of the cell morphotype. 相似文献
8.
Elon Pras Nina Raben Eliahu Golomb Nadir Arber Ivona Aksentijevich Jonathan M. Schapiro Daniela Harel Giora Katz Uri Liberman Mordechai Pras Daniel L. Kastner 《American journal of human genetics》1995,56(6):1297-1303
Cystinuria is an autosomal recessive disease characterized by the development of kidney stones. Guided by the identification of the SLC3A1 amino acid–transport gene on chromosome 2, we recently established genetic linkage of cystinuria to chromosome 2p in 17 families, without evidence for locus heterogeneity. Other authors have independently identified missense mutations in SLC3A1 in cystinuria patients. In this report we describe four additional cystinuria-associated mutations in this gene: a frameshift, a deletion, a transversion inducing a critical amino acid change, and a nonsense mutation. The latter stop codon was found in all of eight Ashkenazi Jewish carrier chromosomes examined. This report brings the number of disease-associated mutations in this gene to 10. We also assess the frequency of these mutations in our 17 cystinuria families. 相似文献
9.
Treatment of Bacillus megaterium cell suspensions with 12 /μmol/1 chlorhexidine diacetate for 5 min led to an approximate 50%, reduction in viability when plated onto tryptone soya agar (TSA). Fifty percent of the surviving fraction were unable to form colonies on TSA containing 5.5% w/v KCI. Such loss of KCl tolerance is indicative of membrane damage, and was recovered within 30 min of incubation in tryptone soya broth (TSB). Multiplication of the damaged organisms did not recommence in this medium until after 60 min. Inclusion of inhibitors of respiration, and of protein, RNA and DNA synthesis in the TSB recovery medium did not significantly affect either the rate or extent of the recovery of KCl tolerance by damaged organisms. 相似文献